This invention relates to a process for displaying measuring results in graphic form in a test apparatus for textile goods such as yarn, roving or sliver, in which a number of individual samples of a batch are tested in the form of a test series and at least a part of the measuring results is displayed in graphic form.
In textile laboratories, especially in spinning factories, spot checks are carried out to determine certain textile parameters such as fluctuations in mass, hairiness, tensile strength, fineness, and twist It is necessary on statistical grounds to test a relatively large number of individual samples from each batch to be tested. These samples are tested in the form of a test series which produces not only results which can be expressed in numerical data but also results which can only be fully expressed by graphs.
Examples of the latter include in particular a diagram showing fluctuations in mass along a tested textile sample, a spectrogram, a length variation curve, and a frequency diagram.
For the diagram of fluctuations in mass, a length scanned in a measuring instrument is kept as short as possible, for example 8 mm, but for reasons of statistical reliability the length of the random sample should be as great as possible. For advantageous operation of a test apparatus, therefore, the sample is drawn at high speed through a measuring instrument so that the mass fluctuations are obtained at relatively high frequencies in the test apparatus.
A spectrogram is a spectrum of wavelengths obtained in the diagram and is generally obtained by a Fourier analysis. The spectrogram gives important indications of the quality of the sample and of the cause of periodic or quasi-periodic faults.
The length variation curve gives the magnitude of the variation coefficient of the mass as a function of the scanning length and also provides information on the quality of the sample and the cause of faults.
Other graphic representations that are obtainable include, for example, line diagrams, force-elongation curves, and modulus-elongation curves.
Present-day computers are able to interpret the data extremely rapidly during the measuring time so that the measuring results can virtually be displayed at the end of the measuring process. Numerical values may be displayed by instruments with pointers or instruments with digital display, while graphs are usually displayed by means of plotters or chart recorders which produce the graphs on a suitable strip of paper.
Chart recorders have, however, numerous disadvantages. First, they are highly susceptible to failure because the pens tend to get blocked in the dusty air of textile laboratories; they are also difficult to operate. Second, their frequency response is very limited so that, for example, the amplitude of the diagrams that are produced decreases with increasing speed of testing. Third, when a chart with a scale is required it is necessary to use special preprinted graph paper and in many cases the recording on the chart must be brought in line with the preprinted marks on the paper. Finally, since the charts obtained with chart recorders are produced in an abnormal format, they must be glued to paper of normal format before they can be filed away.
All of these disadvantages could be overcome by digitally storing the charts during the measuring time and subsequently printing them out on a chart printer, for example during the next measurement in the test series. Since, however, most chart printers are relatively slow the printing, for example of a diagram, a spectrogram or a length variation curve, takes up considerably more time than the next measurement. It follows that in a test series carried out on 10 or 20 random samples, a test apparatus cannot begin the measurement of, for example, the third sample until the printer has printed the results of the second sample, so that pauses occur between the individual measurements of a test series, with the result that the efficiency of the test apparatus is greatly reduced.